Boards of Canada? Committees In Montana?
The first real clue leading away from Boards of Canada was at the Electronic Insurance Bureau, which lists "Lavender Trapezoids" as an album by an artist named CiM for no apparent reason, since it isn't in CiM's discography. No link or further information given. Then, after a google search for "cim lavender trapezoids mislabeled" it was all clear:
"The mislabeled tracks making the rounds on file-sharing services under the title 'Lavender Trapezoids' are all by CiM. 'nskino' is actually 'disco alta', 'rhomboid' is actually 'isempty', etc.; someone's idea of a joke."
So yes, the mp3s are from Simon Walley, aka CiM, from his 2000 release, "Reference" with changed track titles and id3 information.
Now you may be thinking, if you heard these expecting Boards of Canada, that this music is crap. If you did, then you're listening to it in the wrong way. You were surprised by this uninvited guest, so I understand why you're upset. But before you throw him into your recycling bin, remember that Simon stumbled into your home innocently. Someone gave him bad directions as a joke, and the least you could do is give him a place to stay for the evening...
Now that you know for sure the tracks aren't Boards of Canada, you should be able to wipe the slate clean and listen again without expectation.
Here's an mp3 from a 2001 sampler from Emoticon Records:
CiM - Forward (Extended Mix).mp3
And one from the Lush Life compilation on L.A.'s Quango Records:
CiM - Shift.mp3
So rename those mp3s, fix the id3 tags, and listen to them for a few days. You may decide to just go back to listening to older Boards of Canada, but that's fine. Hard drive space is always limited.